This invention relates to an apparatus and method to modify and vaporize liquid hydrocarbons so that they may be burned in a conventional gas burner, more particularly the method is to mix fuel oil with diluent, such as steam, partially vaporize the fuel oil, separate out liquid, superheat the vapor and burn it in a burner designed for natural gas without major modifications to the burner.
This invention is an improvement on the invention in copending application Ser. No. 758,586, of even date, which in turn is a continuation-in-part application of application Ser. No. 549,641, filed Feb. 13, 1975 now abandoned, hereby incorporated by reference.
The general concept of mixing oil and steam to vaporize, and subsequently superheating the mixture, then burning it, is very old as shown in U.S. Pat. Reissue No. 10,699 (1886); U.S. Pat. No. 1,719,397 (1929); and U.S. Pat. No. 1,971,847 (1934).
Also, the general concept of separating liquid from vapor in the effluent of a vaporizer with recirculation of a portion of a separator bottoms to the vaporizer, and with another portion of the separator bottoms drawn off, is old as shown in U.S. Pat. No. 1,842,320 (1932), and U.S. Pat. No. 2,799,628 (1957).
The concept of mixing a diluent gas into a vaporized oil is also disclosed in the prior art such as in U.S. Pat. No. 3,561,895 and in U.S. Pat. No. 1,958,671.
Flashing of liquid (not vapor) oil is known; see U.S. Pat. No. 2,067,940.
Also, it is disclosed in many patents, such as U.S. Pat. No. 3,291,191 and U.S. Pat. No. 3,885,904, mixing oil vapor with air and/or products of oil combustion prior to the burner in order to use normally liquid fuel in conventional gas burners. This explosive mixture is not part of the inventive concept of this patent application.
In U.S. Pat. No. 3,938,934, the concept of warming the air or combustion with warm water to be cooled by means for evaporative cooling such as a cooling tower is disclosed.
In U.S. Pat. No. 3,049,168, the disclosure is limited to simultaneous burning of two fuels from two separate burners, one for each fuel.
The following U.S. patents disclose various control systems for gas burners. U.S. Pat. No. 3,722,811 is directed to a complex control system for a burner. The system controls the flow of two separate fuels and air through a computing relay which computes the heat value of the fuel and also uses a three-way valve receiving signals from measuring devices on the second fuel line and a by-passing conduit hooked to the second fuel line, with all the fuel, air and by-passing conduit flows being measured and monitored in the complex signaling means system. U.S. Pat. No. 3,561,895 discloses feeding fuels of different molecular weights to a burner having constant air flow. This patent discloses the steps of determining the variations and density of the second fuel and adjusting the temperature of the second fuel to equalize the density of the second fuel with the first so as to maintain constant air flow at the burner even though fuels are changed. U.S. Pat. No. 3,291,191 discloses a method of operating a gas burner in interruptable service. The method is (a) terminating the flow of gas, (b) supplying a light petroleum hydrocarbon and (c) mixing the hydrocarbon with air and burning the hydrocarbon. The light hydrocarbon must have an end boiling point not exceeding about 450.degree. F. U.S. Pat. No. 3,285,320 has a disclosure limited to a control system which varies the flow of the fuel in accordance with the specific gravity or varies the flow with the specific gravity plus the Btu value. U.S. Pat. No. 3,049,300 is limited to controlling the combustion zone in a two-fuel furance, such as a blast furnace, to achieve excess air in the stack.
The prior art also teaches the use of steam to atomize oil such as in U.S. Pat. No. 1,766,243 or U.S. Pat. No. 132,440 (1872). The latter patent also superheats the atomized or vaporized oil. For purposes of this patent application, vaporization shall mean changing the liquid fuel oil to a vapor, not merely physically breaking it up into droplets or a fog such as disclosed in the "atomizing" prior art.
The following U.S. patents are of some interest: U.S. Pat. Nos. 3,897,194; 3,614,282; 2,070,209; 3,885,904; 3,463,599; 1,987,400; 3,850,569; 3,236,281; 1,843,757; 3,876,363; 3,159,345; 1,337,144; 3,808,795; 3,107,719; 1,158,687; 3,749,318; 2,975,594; 1,466,250; 3,672,808; 2,972,058; 3,649,230; 2,866,602.